/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.engine.trigger.sink.forward.http;

import org.apache.http.HttpStatus;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.iotdb.db.engine.trigger.sink.api.Handler;
import org.apache.iotdb.db.engine.trigger.sink.exception.SinkException;
import org.apache.iotdb.db.engine.trigger.utils.HTTPConnectionPool;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.List;

public class HTTPForwardHandler implements Handler<HTTPForwardConfiguration, HTTPForwardEvent> {

    private static final Logger LOGGER = LoggerFactory.getLogger(HTTPForwardHandler.class);

    private static CloseableHttpClient client;
    private static int referenceCount;

    private HttpPost request;
    private HTTPForwardConfiguration config;

    private static synchronized void closeClient() throws IOException {
        if (--referenceCount == 0) {
            client.close();
        }
    }

    private static synchronized void openClient() {
        if (referenceCount++ == 0) {
            PoolingHttpClientConnectionManager connectionManager = HTTPConnectionPool.getInstance();
            client = HttpClients.custom().setConnectionManager(connectionManager).build();
        }
    }

    @Override
    public void close() throws IOException {
        closeClient();
    }

    @Override
    public void open(HTTPForwardConfiguration config) {
        this.config = config;
        if (this.request == null) {
            this.request = new HttpPost(config.getEndpoint());
            request.setHeader("Accept", "application/json");
            request.setHeader("Content-type", "application/json");
        }

        openClient();
    }

    @Override
    public void onEvent(HTTPForwardEvent event) throws SinkException {
        CloseableHttpResponse response = null;
        try {
            request.setEntity(new StringEntity("[" + event.toJsonString() + "]"));
            response = client.execute(request);
            if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
                throw new SinkException(response.getStatusLine().toString());
            }
        } catch (Exception e) {
            if (config.isStopIfException()) {
                throw new SinkException("HTTP Forward Exception", e);
            }
            LOGGER.error("HTTP Forward Exception", e);
        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                LOGGER.error("Connection Close Exception", e);
            }
        }
    }

    @Override
    public void onEvent(List<HTTPForwardEvent> events) throws SinkException {
        CloseableHttpResponse response = null;
        try {
            StringBuilder sb = new StringBuilder().append("[");
            for (HTTPForwardEvent event : events) {
                sb.append(event.toJsonString()).append(", ");
            }
            sb.replace(sb.lastIndexOf(", "), sb.length(), "").append("]");
            request.setEntity(new StringEntity(sb.toString()));
            response = client.execute(request);
            if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
                throw new SinkException(response.getStatusLine().toString());
            }
        } catch (Exception e) {
            if (config.isStopIfException()) {
                throw new SinkException("HTTP Forward Exception", e);
            }
            LOGGER.error("HTTP Forward Exception", e);
        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                LOGGER.error("Connection Close Exception", e);
            }
        }
    }
}
